Its exactly how CASTLE is supposed to look.
People have the idea of castle from Disney and late renaissance era, when castles were just fancy manors.
Real, mid medieval castles looked like this. Wall surrounding simple multiple structures which housed the family, soldiers and servants, also stables and grain silos.
They were not made to be fancy, they were meant to be practical. Winterfell was based on castles in Scotland from the War of the Roses period. Which is period that inspired Martin to write Game of Thrones.